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Extragalactic abstracts - IRSA - California Institute of Technology

Extragalactic abstracts - IRSA - California Institute of Technology

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Spitzer_Approved_<strong>Extragalactic</strong><br />

Mar 25, 10 16:24 Page 565/742<br />

Spitzer Space Telescope − General Observer Proposal #50753<br />

Infrared Search for Hidden Active Galactic Nuclei<br />

Principal Investigator: Michael Werner<br />

Institution: JPL<br />

Technical Contact: Varoujan Gorjian, JPL<br />

Co−Investigators:<br />

Daniel Stern, JPL<br />

Kieran Cleary, JPL<br />

Stephen Murray, Harvard Smithsonian Center for Astrophysics<br />

Christine Jones, Harvard Smithsonian Center for Astrophysics<br />

William Forman, Harvard Smithsonian Center for Astrophsyics<br />

Ryan Hickox, Harvard Smithsonian Center for Astrophysics<br />

Varoujan Gorjian, JPL<br />

Science Category: AGN/quasars/radio galaxies<br />

Observing Modes: IrsStare<br />

Hours Approved: 19.7<br />

Abstract:<br />

In 1982 Elvis et al called attention to a pair <strong>of</strong> galaxies with AGN−like x−ray<br />

emission but no AGN features in their visible spectra [referred to here as<br />

XBONGS]. Since then, deep x−ray surveys [Moran et al 2002] have revealed large<br />

numbers <strong>of</strong> galaxies with these characteristics: luminous in the x−ray but<br />

without the high excitation lines, specific line ratios, or broad emission lines<br />

which characterize Type I and/or Type II AGN. Thus understanding XBONGS is an<br />

important step towards defining the accretion history <strong>of</strong> the Universe. For<br />

brevity, we continue to refer to these objects as XBONGS, while recognizing that<br />

they are not a homogeneous group, and in fact a variety <strong>of</strong> explanations have<br />

been proposed. It has been suggested that XBONGs are powered by AGN which are<br />

hidden at visible wavelengths by (i) dilution by the bright emission from the<br />

galaxy, by (ii) extinction, or by (iii) the absence <strong>of</strong> visible and ultraviolet<br />

radiation due to modifications in the character <strong>of</strong> the accretion disk which<br />

surrounds the central black hole. These suggestions can be tested by infrared<br />

observations, so we propose here a program <strong>of</strong> IRS spectroscopy <strong>of</strong> 8 XBONGs<br />

carefully selected from 26 XBONGs identified in the XBootes survey <strong>of</strong> the NOAO<br />

Deep Wide−Field Survey. We will observe the [NeV] 14.3um and the [NeIII] 15.6um<br />

lines to identify and characterize the hidden AGN in these galaxies, drawing on<br />

our published Spitzer observations <strong>of</strong> these lines in AGN with known x−ray<br />

emission. We hope to distinguish among the competing models for the XBONG<br />

phenomenon and to make an assessment <strong>of</strong> this problem as part <strong>of</strong> the legacy <strong>of</strong><br />

the cryogenic Spitzer mission.<br />

Spitzer_Approved_<strong>Extragalactic</strong><br />

Printed_by_SSC<br />

Mar 25, 10 16:24 Page 566/742<br />

Spitzer Space Telescope − Guaranteed Time Observer Proposal #86<br />

Imaging and Spectroscopy <strong>of</strong> X−ray Selected Seyfert Galaxies<br />

Principal Investigator: Michael Werner<br />

Institution: JPL<br />

Technical Contact: Varoujan Gorjian, JPL<br />

Science Category: AGN/quasars/radio galaxies<br />

Observing Modes: IrsStare MipsPhot<br />

Hours Approved: 23.5<br />

Abstract:<br />

In present unified schemes, dust plays a major role in determining Seyfert<br />

types, with Seyfert 1’s being less obscured and Seyfert 2’s being more obscured,<br />

but both with the same underlying energy generation mechanism, an accretion disk<br />

around a supermassive black hole. We have chosen to study a group <strong>of</strong> Seyferts at<br />

two wavelengths that are least affected by dust obscuration: x−rays and<br />

infrared. Our sample is a mix <strong>of</strong> Seyfert 1’s and Seyfert 2’s which have been<br />

observed in the x−rays, for which we will obtain IR spectra with all IRS<br />

modules, and photometry at 25 and 70 microns with MIPS. By comparing the<br />

characteristics <strong>of</strong> these two penetrating data sets we will be able to constrain<br />

better the role <strong>of</strong> dust in the nuclei <strong>of</strong> these active galaxies, especially the<br />

large column densities (>10^25 Hydrogen atoms per cm^2) derived from x−ray<br />

observations.<br />

Thursday March 25, 2010 xgal_covers.txt<br />

283/371

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